Device for finishing a workpiece surface with pivoting print head

Abstract

The invention relates to a device for finishing a surface, preferably a narrow surface, of a workpiece, which preferably consists at least partially of wood, wood-based materials, or the like, with a printing unit. The device comprises a printing unit with one or more printheads, each printhead being rotatable about its own vertical axis and relative to the printing unit by means of a pivoting element, and / or the one or more printheads together with the printing unit being rotatable about a common vertical axis, preferably equidistant from each printhead, and allowing a translational relative movement between the printing unit and the workpiece and a rotational movement of at least one printhead to be carried out simultaneously.

Description

Technical field

[0001] The invention relates to a device for finishing a surface, preferably the narrow surface, of a workpiece, which preferably consists at least partially of wood, wood-based materials or the like, with a pressure unit. State of the art

[0002] Known devices for decorating or refining the narrow surfaces or other surfaces of workpieces made of wood, wood-based materials or the like, by means of digital printing, have several print heads that are arranged linearly next to each other and are firmly connected to a printing unit.

[0003] To print on the narrow surfaces of workpieces, a part of such a device with the print heads is guided past the surface of the workpiece to be finished.

[0004] However, with such a device it is not possible, for example, to print or otherwise finish narrow surfaces of workpieces that do not have a straight contour, but rather outer or inner radii, kinks or similar features.

[0005] A device for printing on surfaces with several movable printheads according to the preamble of claim 1 is known from DE 10 2012 005 087 A1.

[0006] A device for inkjet printing on a complex surface is known from FR 3 087 705 A1. A device for producing components with a predetermined surface appearance, in particular front panels of kitchen units, is known from US 2004 / 0028830 A1. A method and a device for manufacturing a component with a surface of predetermined appearance are known from EP 2 292 437 A1. Description of the invention

[0007] The invention is based on the objective of providing a device for finishing a surface, preferably a narrow surface, of a workpiece, which makes it possible to finish surfaces or narrow surfaces of such workpieces, in particular to print on them, which have non-linear workpiece contours such as radii, kinks or the like.

[0008] This problem is solved according to the invention by a device according to claim 1. Particularly preferred, advantageous embodiments of the invention are specified in the dependent claims.

[0009] According to the invention, the device for finishing a surface, in particular a narrow surface, of a workpiece, which preferably consists at least partially of wood, wood-based materials, or the like, comprises a printing unit. The printing unit and the workpiece can be moved translationally relative to each other. The printing unit has one or more printing heads. Each printing head can be pivoted about a vertical axis of the respective printing head and relative to the printing unit by means of a pivoting element, and / or the one or more printing heads can be pivoted together with the printing unit about a common vertical axis, preferably equidistant from each printing head. A translational relative movement between the printing unit and the workpiece and a rotational movement of at least one printing head are carried out simultaneously.

[0010] Such a device allows the printhead with the printing unit and the workpiece surface to be finished to be moved past each other, and at least one printhead can simultaneously be rotated to align it so that the print media outlet of the printhead is always at a desired angle to the surface being finished, largely independent of the contour of the surface. This alignment of the printhead, or rather its print media outlet, to the surface allows the surface to be finished with the desired quality, for example, by printing a desired design, without unwanted distortions.

[0011] A device that allows multiple printheads to be individually swiveled relative to the printing unit enables the finishing of even narrow surfaces in a single pass using multiple printheads. This allows the surface to be printed directly with multiple media, such as several colors, even if the printing unit only passes over the surface once. In other words, only a single pass is required to completely finish the surface. Furthermore, it is advantageous that only one energy unit is needed for at least the partial curing of the various layers, since the layers from the different printheads can be applied in a single pass. Additionally, the individual swiveling of the printheads relative to the printing unit allows for even greater adaptation to the workpiece contour, thereby further increasing the precision and quality of the print.

[0012] A device in which one or more printheads can be rotated together with the printing unit eliminates the need for separate pivoting elements for each printhead. This reduces costs and maintenance while increasing the device's reliability. The common rotation around a vertical axis equidistant from each printhead ensures that each printhead rotates through the same angle. This further enhances print precision and quality, as each printhead performs the same movement when controlled by the same input.

[0013] In the translational relative movement between the printing unit and the workpiece, either the printing unit can be moved along the contour of the workpiece, the workpiece can be guided past the printing unit according to its contour, or the printing unit and workpiece can each move independently. The overall movement of the print head relative to the surface (especially the narrow edge) of the workpiece to be finished comprises the rotational movement of at least one print head and the translational movement of the printing unit or the workpiece. The translational movement of the printing unit or the workpiece need not be purely translational but can also be superimposed with a rotational movement.

[0014] The described printing unit can print on irregular surfaces, such as surfaces with a cutout, (handle) recess, indentation, or similar feature. When printing on such a surface, the number of active nozzles can be varied during a swiveling motion.

[0015] According to a preferred embodiment, the device is further configured such that the printing unit and the workpiece are moved translationally relative to each other in such a way that the printhead always maintains the same distance from the surface (in particular, the narrow edge) of the workpiece to be finished during the translational relative movement. The device is also configured such that, during the translational relative movement between the printing unit and the workpiece, the printhead is moved by a rotation about the vertical axis such that the printhead and / or a print media outlet of the printhead is oriented at a constant angle, preferably orthogonal, to the surface of the workpiece to be finished.

[0016] Such a device, in which the distance between the printhead and the surface to be finished remains constant during the relative movement of the printing unit and the workpiece, ensures that the layer thickness of the finish or decoration applied during this relative movement is constant across the entire surface. This also prevents distortions in the size of the decoration. An orientation of the printhead, in which the printhead and / or the print media outlet of the printhead are always aligned at a specific angle, preferably orthogonally, to the surface to be finished, can likewise prevent unwanted variations in layer thickness and perspective distortions of the decoration.

[0017] In this context, an orthogonal alignment or an alignment at a specific angle of the printhead to the surface to be finished means that, in particular, the print media outlet, i.e., the opening of the printhead (print media outlet), through which, for example, an ink jet emerges, is aligned to the surface of the workpiece to be finished in such a way that an imaginary extension of such an ink jet and the surface (especially the narrow surface) intersect at an angle of 90° or the specified angle.

[0018] According to a preferred embodiment, the device is further designed such that the translational relative movement between the printing unit and the workpiece and the rotational movement of at least one print head along a contour of the workpiece are carried out, wherein an alignment of the printing unit, print head and workpiece to each other is carried out by manual control, a positive guidance with a touch probe, a control with sensors or on the basis of geometric data of the workpiece.

[0019] Additionally or alternatively, geometry data can be used to calculate the movement of the workpiece, the printing unit or the print heads by means of a control and / or regulation unit and to move the corresponding unit.

[0020] Manual control of the printing unit increases the flexibility of the device, as, for example, certain areas of the surface to be finished can be finished multiple times or under different conditions such as angle or distance if required.

[0021] Controlling the printing unit with sensors enables particularly precise finishing results, as the distance and angle of the printhead to the surface being finished can be precisely adjusted to the desired value. Furthermore, with sensor-based control, finishing can be carried out even without knowledge of the workpiece's exact geometry, since the necessary parameters, such as the angle and distance of the printhead from the device, are automatically adjusted for each individual workpiece. After finishing, the same sensors can be used to check the quality of the applied finish, such as the layer thickness. For this purpose, if the sensors are located on the printing unit, they can be moved along the surface of the workpiece being finished once more.

[0022] By aligning the print head using geometric data, for example from a CAD file, the surface of the workpiece to be finished can be precisely finished, even without the need for costly or potentially error-prone sensors.

[0023] According to a preferred embodiment, at least one printhead has its own working stroke, by which the printhead can be moved translationally relative to the printing unit and by which the distance of the printhead to the workpiece can be changed.

[0024] The precision with which the device refines a surface to be finished can be further increased by having its own working stroke for the print head, since the lower inertia of the print head compared to the printing unit allows the distance between the print head and the narrow surface of the workpiece to be set with less fluctuation.

[0025] According to a preferred embodiment, the device is further designed such that at least one printhead can be exchanged in the printing unit by means of a tool changing system. Thus, the printing unit can be exchanged for other machining tools (milling cutters, drills, etc.) using a tool changing system. This design is particularly suitable for CNC applications.

[0026] This design increases the device's versatility. For example, in addition to printheads used to print the surface to be finished in specific colors, printheads for sealing the surface or applying adhesive can be interchanged in the same printing unit and used for finishing.

[0027] According to a preferred embodiment, the device is further designed such that the one printhead or the multiple printheads and the printing unit can be pivoted together about a common horizontal axis.

[0028] This design allows the device to be used to refine surfaces that are not at least partially orthogonal to a workpiece's support surface. For example, it can be used to refine chamfers on flat workpieces that form a transition between a narrow edge and a flat side of the workpiece. Furthermore, such a device can be used to refine narrow edges of flat workpieces that are not orthogonal to the workpiece's flat sides, but rather inclined at a specific angle, such as 45°, to a flat side of the workpiece.

[0029] According to one embodiment, the device comprises a motion unit, in particular a 5-axis or 6-axis head, for moving the pressure unit relative to the workpiece. This allows the device to be used flexibly in CNC applications.

[0030] Furthermore, according to one embodiment, the pressure unit can be exchanged for other machining tools (e.g., milling cutters, drills, etc.) using a tool changing system. This further increases the flexibility of the device. Brief description of the drawings

[0031] Further features and advantages of the device will become apparent from the following description of embodiments with reference to the accompanying drawings. These drawings show: Fig. 1 is a schematic top view of a printing unit 3 with printheads 2 oriented towards a surface 4 of a workpiece 1 to be finished, which moves linearly relative to the workpiece according to the prior art. The orientation of the printheads 2 is indicated by arrowheads. Fig. 2 is a schematic top view of a printing unit 3 according to the prior art and of a workpiece 1 with an uneven surface 4 to be printed, which cannot be printed by the printing unit 3 shown. Fig. 3 is a schematic top view of a printing unit 3 rotatable and displaceable through 360° with several outwardly oriented printheads 2 with their own working stroke, several curing lamps 5, and a control unit 6 for printing an uneven surface 4 of a workpiece 1 to be finished according to an embodiment of the invention.Fig. 4 A schematic top view of a rotatable and movable printing unit 3 with several individually pivotable printheads 2, each with its own working stroke, oriented towards a surface 4 of a workpiece 1 to be finished, for printing on an irregular surface 4 of a workpiece 1 to be finished, according to one embodiment of the invention. Fig. 5 A schematic perspective view of a printing unit 3, which is movable in the direction of the x, y, and z axes and pivotable about the vertical z-axis (C-axis) and swiveling about the horizontal x-axis (A-axis), with several individually pivotable printheads 2, each with its own working stroke, for printing on an irregular surface 4 of a workpiece 1 to be finished, according to one embodiment of the invention.6. A schematic perspective view of two workpieces 1, each with surfaces 4 to be finished, which are not orthogonal to a support surface of the workpiece, but either form a transition between the narrow surface and the flat side of the workpiece 1 in the form of a chamfer, or are narrow surfaces that are inclined at less than 90° to the flat side of the workpiece 1. Detailed description of embodiments

[0032] Identical reference symbols listed in different figures name identical, corresponding, or functionally similar elements.

[0033] A device for finishing a surface 4, preferably a narrow surface, of a workpiece 1, which preferably consists at least partially of wood, wood-based materials or the like, according to a first embodiment of the invention is in Fig. 3 schematically shown in a top view.

[0034] An example of a surface to be finished is one that comprises several areas at different angles to each other. For example, it could start as a flat surface, then transition into a recess, (handle) groove, indentation, or similar feature, and then back to a flat surface (variable angle of the A-axis). The height of the area to be printed can also be variable.

[0035] The device according to one embodiment comprises a printing unit 3 on which several printheads 2 are arranged. The printing unit 3, together with at least one printhead 2, can be rotated about a vertical axis, preferably the vertical axis of the printing unit, preferably by at least 360°.

[0036] A vertical axis is defined as an axis extending in a direction orthogonal to the translational relative movement between the pressure unit and the workpiece, and parallel to the surface being machined. In CNC machining, the vertical axis is also referred to as the C-axis.

[0037] According to a preferred embodiment, the device is further designed such that the printing unit can be pivoted rotatorily about a horizontal axis.

[0038] A horizontal axis is defined as an axis that extends in the translational direction of relative movement between the pressure unit and the workpiece and is parallel to the surface to be finished. In CNC machining, the horizontal axis is also referred to as the A-axis.

[0039] The pressure unit can preferably be inserted into a tool or aggregate holder of a spindle unit and rotated through it.

[0040] Printheads 2 can preferably be ink-jet printheads, from which ink droplets are ejected and with which a surface can thus be printed.

[0041] If the surface 4 of the workpiece 1 to be finished is printed, a separate printhead can be provided for each primary color, such as cyan, magenta, yellow, and black. The printing unit 3 can include, in addition to at least one printhead, a control unit 6 (control electronics), an ink reservoir, and a power unit 5, such as a curing lamp, a UV lamp, or similar device, suitable for at least partial drying or curing of the finish or print. A separate power unit 5 can be provided for each printhead.

[0042] The device is generally designed so that during the finishing or printing process, the device and the workpiece are moved past each other along the workpiece's contour. This can be achieved either by moving the workpiece along the device's contour, by moving the device along the workpiece's contour, or by moving both the device and the workpiece simultaneously.

[0043] When finishing or printing the surface to be finished with the device according to the instructions in Fig. 3In the schematically illustrated embodiment, a printhead is first selected, for example, based on the color to be printed. This printhead is then guided along the surface of the workpiece to be finished. The printing unit, together with the printheads, rotates around the vertical axis, which is preferably the vertical axis of the printing unit, such that a nozzle outlet of the selected printhead is always at a specific angle, preferably orthogonal to the surface to be finished. The energy unit 5 of the selected printhead can at least partially cure the finish applied by the printhead to the surface to be finished.After the selected printhead has completely finished the surface of the workpiece to be finished and has been guided along it, the next printhead is selected, for example based on its color to be printed, and is also guided along the surface of the workpiece to be finished, whereby the printing unit performs a rotation around the vertical axis in such a way that a nozzle media outlet of the printhead is always aligned orthogonally to the surface to be finished.

[0044] Each printhead 2 of the printing unit 3 can have its own working stroke. This working stroke allows the printhead to be moved, at least translationally, relative to the printing unit. The distance of the printhead to the surface 4 of the workpiece 1 to be finished can be adjusted by this working stroke. Thus, this distance can be adjusted in addition to the distance achieved by positioning the printing unit relative to the surface to be finished. The distance of the printhead to the surface to be finished can be set so that it remains constant throughout the finishing process.

[0045] A second preferred embodiment of the device is described in Fig. 4 schematically shown in a top view.

[0046] The device according to one embodiment comprises a printing unit 3 on which several printheads 2 are arranged. The printing unit, together with at least one printhead, can be rotated about a vertical axis, which is preferably the vertical axis of the printing unit. Furthermore, each printhead 2 of the printing unit 3 can have its own pivoting element with which the printhead 2 can be rotated relative to the printing unit 3 about another vertical axis, which is preferably the vertical axis of the printhead 2. Each printhead 2 can also have its own working stroke with which the printhead 2 can be moved translationally relative to the printing unit 3 and the distance between the printhead 2 and the surface 4 of the workpiece 1 to be finished can be further adjusted, as described above.If the surface 4 of the workpiece 1 to be finished is printed, a separate printhead can be provided for each base color, such as cyan, magenta, yellow, and black. In addition to at least one printhead, the printing unit 3 can also include a control unit 6 (control electronics), an ink reservoir, and a power unit 5, such as a curing lamp, a UV lamp, or similar device, suitable for at least partially drying or curing the finish or print. Preferably, the printing unit can also have only a single power unit 5 for at least partially curing or drying the finish, since the multi-layered finish can be applied in a single pass with this device.

[0047] When finishing or printing the surface to be finished with the device according to the instructions in Fig. 4In the schematically illustrated embodiment, the printing unit 3 is guided along the surface 4 of the workpiece 1 to be finished. The printing unit 3, together with the printheads 2, can rotate about the vertical axis, which is preferably the vertical axis of the printing unit 3. Furthermore, each of the printheads 2 can rotate about another vertical axis, preferably the vertical axis of its respective printhead 2. The device performs the rotation of the printing unit 3, the rotation of the printhead 2, or a combination of both rotations, such that each printhead is always at a specific angle, preferably orthogonal, to the surface 4 to be finished. The energy unit of the printing unit can at least partially cure the finish applied to the surface to be finished by the printheads.The distance between the print head and the surface to be finished can be adjusted so that this distance remains constant throughout the finishing process.

[0048] The described printing unit can print on irregular, and therefore complex, surfaces, such as the surfaces of a recess, handle, indentation, or similar. When printing on such a complex surface, the number of active nozzles can be varied during a single swiveling motion.

[0049] A further development of the first or the second preferred embodiment is described in Fig. 5 depicted.

[0050] The printing unit 3 is translationally displaceable in the x, y, and z axes and pivotable about the vertical z-axis (C-axis). Furthermore, the printing unit 3 is pivotable about the horizontal x-axis (A-axis). The printing unit 3 has one or more printheads 2, each with its own working stroke, which can optionally be rotated relative to the printing unit 3 by means of their own pivoting elements.

[0051] Because the printing unit 3 can be pivoted around the horizontal x-axis (A-axis), the surfaces of chamfers on flat workpieces can also be finished, for example, those forming a transition between the narrow surface and the flat side of the workpiece.

[0052] Furthermore, such a device can be used, for example, to finish narrow surfaces of flat workpieces that are not orthogonal to the flat sides of the workpiece, but are inclined to a flat side of the workpiece at a certain angle, for example 45°.

[0053] Examples of workpieces with such surfaces to be finished (4) are in Fig. 6 shown, with a workpiece 1 with a chamfer in the transition between the narrow surface and the flat side (wide surface) of the workpiece 1 shown in the upper left and a workpiece 1 with a narrow surface that is not orthogonal to the flat side of the workpiece 1, but is inclined at a certain angle in the lower right.

[0054] It is evident to a person skilled in the art that individual features described in different embodiments can also be implemented in a single embodiment, provided they are not structurally incompatible. Likewise, various features described within a single embodiment can also be provided individually or in any suitable subcombination in several embodiments.

Claims

1. Device for finishing a surface (4) of a workpiece (1) which preferably consists at least in part of wood, wood-based materials or the like, which device comprises a pressure unit (3), wherein the pressure unit (3) and the workpiece (1) can be moved in a translational manner relative to one another; and the pressure unit (3) comprises a plurality of pressure heads (2), characterised in that each pressure head (2) is pivotable in a rotational manner by means of a pivot element relative to the pressure unit (3) about a vertical axis of the relevant pressure head that extends in a direction that is orthogonal to the translational movement direction between the pressure unit and the workpiece and parallel to the surface to be finished; the device is configured to carry out the translational relative movement between the pressure unit (3) and the workpiece (1) and the rotational movement of at least one pressure head (2) at the same time; and the plurality of pressure heads (2) and the pressure unit (3) are pivotable together in a rotational manner about a common horizontal axis which extends in the translational relative movement direction between the pressure unit and the workpiece and parallel to the surface to be finished.

2. Device according to claim 1, which is further designed such that the pressure unit (3) and the workpiece (1) are moved in a translational manner relative to one another in such a way that at least one pressure head (2) is held at a constant distance from the surface (4) of the workpiece (1) to be finished during the translational relative movement; and in that the pressure head (2) is moved by means of a rotation about the vertical axis in such a way during the translational relative movement between the pressure unit (3) and the workpiece (1) that a pressure media outlet of the pressure head (2) is oriented at a constant angle, preferably orthogonally, to the surface (4) of the workpiece (1) to be finished.

3. Device according to claim 1 or 2, which is further designed such that the translational relative movement between the pressure unit (3) and the workpiece (1) and the rotational movement of at least one pressure head (2) are carried out along a contour of the workpiece (1), wherein an orientation of the pressure unit (3), pressure head (2) and workpiece (1) relative to one another is carried out by means of manual open-loop control, forced guidance with a contact apparatus, closed-loop control with sensors, calculation of the paths of the workpiece, pressure unit and / or pressure head, or based on geometric data of the workpiece (1).

4. Device according to any of the preceding claims, wherein at least one pressure head (2) has its own working stroke by which the pressure head (2) can be moved in a translational manner relative to the pressure unit (3) and by which a distance between the pressure head (2) and the surface (4) of the workpiece (1) to be finished can be changed.

5. Device according to any of the preceding claims, which is designed such that at least one pressure head (2) can be replaced in the pressure unit (3) by means of a workpiece replacement system.

6. Device according to any of the preceding claims, comprising a movement unit, in particular a 5-axis or 6-axis head, for moving the pressure unit (3) relative to the workpiece (1).

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